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How to Reduce the Minimum Fan Speed of a nVidia GT430 Graphics Card

If you have an nVidiaGeForce GT 430 graphics card and you want to reduce the card’s minimum fan speed, then these instructions should help you achieve that with relative ease.

ASUS 1GB GeForce GT 430 PCI-E 2.0 with Low Profile Bracket

Introduction

Cards like the ASUS 1GB GeForce GT 430 graphics card are often incorporated in slim Home Theatre PCs (HTPC) because of their low profile fit and their relatively low cost coupled with their high performance at decoding High Definition (HD) video content.

These models have a cooling fan sat inside the heat sink that helps govern the temperature of the GPU. The minimum fan speed is set in the card’s BIOS as a percentage of it’s top rotational speed. My card’s minimum fan speed was set at 60%. I had read of other minimum fan speeds, such as 65%, when I started to research this.

Initially, the card was quiet enough for use in my HTPC. Over time however, the fan became louder at it’s minimum, idling speed. And I wanted to quieten it down by reducing it’s minimum speed and adjusting the fan’s speed v GPU temperature curve. I found I could do most things with software except reduce the hard-coded minimum fan speed. A BIOS hack was required.

I found that a great number of people had been asking how to do this hack via many different internet forums. Solutions were not clear; the posts were old and a lot of the links for the necessary software were dead.

I found two noteworthy sets of instructions here to flash the device from a bootable usb stick running DOS. No matter how I tried though, I couldn’t get mine to flash. And I think it’s because the software revisions have moved on.

Download NiBiTor and nvflash (windows version) and unzip them if necessary by extracting them to their own folders. Remember their locations.

Download and install EVGA Precision X on your computer.

Click once on Windows Start and type in cmd where it says Search programs and files. Do not press Enter.

The cmd program should be shown at the top of the list under the heading: Programs. Right click on it once and select Run as administrator. Click Yes when prompted.

The command console should appear and look something like this:

Double click the nvflash folder and right click on the directory path at the top of the folder window.

Select Copy address text from the context menu.

You can see here that my nvflash folder resides on my F drive at
F:\GT430 BIOS FLASH\nvflash_windows_5.142

Now click on the cmd window and type cd and a space. Right click and select paste.
The full directory name should be pasted into the window like this:

Press Enter to change into that directory. Notice that if you have your files on a different drive to C, you will have to change to that drive before hand like I have done here with F:

Back Up the Original ROM

In the cmd window, type

nvflash -b original.rom

and press Enter

This will make a back up copy of the nVidia card’s BIOS to your nvflash directory with the filename

original.rom

You can use a filename of your choice.

It is important at this stage to make back up copies of this BIOS image. Store a copy on a usb stick. Store a copy on another PC. Should things go wrong, you will need access to this file. A bad flash may prevent your card from outputting any display at all. So it’s no good just to have the one copy on that machine. You won’t be able to see to get at it!

Modify the BIOS with NiBiTor

Go into your NiBiTor folder and run the program.
Go to File > Open BIOS…
and select the file original.rom from your nvflash directory

You should see something like this as you browse the different tabs:

Change the Min fan speed here to something like 30

Then go to File > Save BIOS…

and select a new name for you modified ROM. Ensure you don’t overwrite your back up file.

Save this file to your nvflash directory. I used the filename:

modified.rom

Ready to Flash the BIOS?

The files in your nvflash directory should look something like this:

The nvflash files; the modified BIOS and your back up file.

Note: I have two back up files of the original BIOS in this screenshot entitled backup.rom and GF108.rom. You will just have the one back up file entitled original.rom

WARNING: The next command starts the flash process!

Ensure that this process is not going to be interrupted by anything.

DO THIS AT YOUR OWN RISK

Click on the cmd window once more and type:

nvflash modified.rom

and press Enter

The BIOS will be flashed with your modifications. Wait until the program reports success, then reboot your PC.

In the event that the flash goes wrong, you will need your original BIOS rom file to attempt a blind flash using a usb stick. Details of how to do this are explained in the links I gave in the introduction.

Controlling Fan Speed

Launch EVGA Precision X

Tick Windows Start Up so the software runs every time Windows boots. If you click on the settings icon (the two gears in mesh – top right) you will be able to select Start minimized if you don’t want this screen to appear every time Windows starts.

Change the minimum speed of the fan. (I believe that there is another value in the BIOS that prevents the fan from stalling at low rotational speeds). I found I couldn’t enter values less than 31% even though I’d set the minimum value in my modified BIOS to 20.

Ensure Auto is ticked.

Now click on fan curve and ensure that Enable software automatic fan control is ticked

Here you can drag the points on the curve to create your own profile of fan speed vs GPU temperature. Experimentation and monitoring is key here. Spend a while monitoring your GPU temperature under different conditions of load. Playing games for example will cause the GPU to generate lots of heat. That heat has to be dissipated effectively or your GPU will burn out.

This profile works for me but the sole use of my card is the decoding of HD video. What I’ve done here is:

halve the fan’s minimum speed

keep the fan at it’s new minimum speed until the GPU temperature hits 68’C